This removes the parameter `time_zone` from the request. It's kept in
the configuration and always initialized to `UTC`.

The parameter will be added back later with broader support for time
zones.

## Summary

Support for the `time_zone` request param was temporarily removed from
ES|QL in elastic/elasticsearch#102767. This
caused some of our tests to fail since we include the `time_zone` param
in ES|QL requests in Kibana. This PR comments out the `time_zone`
related code until support is reintroduced in ES|QL, and unskips the
broken tests.

The followup work to uncomment the code when `time_zone` support is
reintroduced to ES|QL will be done in #172221.

Resolves #172215.
Resolves #172213.
Resolves #172242.
Resolves #172243.
Resolves #172244.

### Checklist

- [ ] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/packages/kbn-i18n/README.md)
- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
- [ ] Any UI touched in this PR is usable by keyboard only (learn more
about [keyboard accessibility](https://webaim.org/techniques/keyboard/))
- [ ] Any UI touched in this PR does not create any new axe failures
(run axe in browser:
[FF](https://addons.mozilla.org/en-US/firefox/addon/axe-devtools/),
[Chrome](https://chrome.google.com/webstore/detail/axe-web-accessibility-tes/lhdoppojpmngadmnindnejefpokejbdd?hl=en-US))
- [ ] If a plugin configuration key changed, check if it needs to be
allowlisted in the cloud and added to the [docker
list](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)
- [ ] This renders correctly on smaller devices using a responsive
layout. (You can test this [in your
browser](https://www.browserstack.com/guide/responsive-testing-on-local-server))
- [ ] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)

### For maintainers

- [ ] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

Tests were skipped in #172260 due
to errors related to ES API changes
elastic/elasticsearch#102767

Errors originated in DIscover component and have been fixed in
#172220